Ray Bowman, O'Donnell Lab
Defining the ubiquitin-dependent interactome of α-arrestins and their function in autophagy
Cells respond to cues in their extracellular environment by selectively redistributing proteins. This reorganization is imperative for cell survival and is regulated, in part, by alpha-arrestins. How then is α-arrestin-mediated trafficking controlled? We know that modification by ubiquitination plays a role in modifying α-arrestin function. To help us identify specific α-arrestin regulators, we generated and utilized a unique yeast gene deletion library called the Saccharomyces cerevisiae Ubiquitin Interactome (ScUbI) library. ScUbI contains all the non-essential genes annotated as important for ubiquitination/ubiquitin interaction. The ScUbI library was transformed with plasmids over-expressing α-arrestins Aly1 and Aly2, then assessed for gene deletions that either increased or decreased cells sensitivity to rapamycin, an inhibitor of TORC1 function that mimics nitrogen starvation. Gene Ontology enrichment analysis identified autophagy as the most strongly enriched category amongst candidates. Genetic interactions were confirmed for a number of autophagy-related genes, and we initially chose Atg7 for follow up analysis. Those studies demonstrated that in atg7∆ cells Aly1 and Aly2 electrophoretic mobility is altered. This mobility shift is due to hyper-phosphorylation of the α-arrestins in the absence of Atg7. Live cell imaging and biochemical analysis have also revealed α-arrestin-dependent changes in autophagic flux and the abundance of autophagy-specific protein Atg8. These and additional data support an exciting novel role for α-arrestins as regulators of autophagy, which expands on their known function in sensing and responding to nutrient stress.
Friday, October 26th
12 PM
Langley Hall A219B